Iris diaphragm with extra leaf for complete closure

ABSTRACT

An iris diaphragm with a set of iris leaves, pivoted to a fixed mounting ring, and a set of control leaves, articulated to respective iris leaves and pivoted to a rotatable setting ring, further includes an extra leaf pivoted to the mounting ring and coupled with one of the control leaves through a pin engaging in an L-shaped groove whereby, in a limited inwardly swung position of the iris leaves, further rotation of the setting ring cams the extra leaf into a stop position obstructing the residual aperture.

United States Patent [1 3,668,995 Bardutzky June 13, 1972 [54] IRIS DIAPHRAGM WITH EXTRA LEAF 2,944,477 7/1960 Tesch ..95/64 R FDR COMPLETE CLOSURE 2,949,076 8/1960 Finkl 3,055,282 9/1962 Bauer et al.. [72] Inventor: Klaus Bardutzky, Bad Kreuznach, Ger- 3,438,316 4/1969 Rodier many [73] Assignee: Jos Schneider & Co., Bad Kreuznach, Geri y m 1311 Peters many Attorney-Karl F. Ross [22] Filed: Dec. 18, I969 ABSTRACT [21] Appl' No; 886425 An iris diaphragm with a set of iris leaves, pivoted to a fixed mounting ring, and a set of control leaves, articulated to [30] Foreign Application Priority Data res ective iris leaves and pivoted to a rotatable setting ring,

P Dec 18 1968 German v P 18 l 5 349 6 further includes an extra leaf pivoted to the mounting ring and y coupled with one of the control leaves through a pin engaging 52 U.s. Cl. ..95/64 R L5MPed whereby in a limited inwardly swung [51] 9/06 position of the iris leaves, further rotation of the setting ring 58 Field of Search ..95/63, 64 R Cams the extra leafinto a p Position obstructing the residual aperture. [5 6] Referenes med 7 Claim, 4 Drawing Figures UNITED STATES PATENTS 622,592 4/1899 Berger ..95/64 R PATENTEDJUH13 m2 I 3,668,995

l N VENTOR.

" Attorney Klaus Bardufzky coaxial coupling formations to swing withdrawn position into a stop position obstructing the FIELD OF THE INVENTION My present invention relates to an iris diaphragm for photographic, cinematographic or television cameras.

BACKGROUND OF THE INVENTION Conventional iris diaphragms include a pair of relatively rotatable coaxial rings, generally a fixed mounting ring and an adjustable setting ring, as well as a set of peripherally equispaced iris leaves which are jointly swung toward or away from the ring axis upon relative rotation of the rings in one sense or the other to narrow or to widen a central aperture defined by inner edge portions of these leaves.

In one type of iris diaphragm, to which this invention pertains, the swing of the iris leaves is brought about by advantageously leaf-shaped control elements which are articulated to respective iris leaves while being pivoted to the setting ring, the iris leaves in turn being pivoted to the mounting ring. in a terminal position of rotation, the pivot of any control leaf lies substantially opposite its point of articulation to the associated iris leaf so that further rotation of the setting ring beyond this terminal position will not bring the iris leaves closer to the axis. This terminal ring position, therefore, coincides with 'a limiting leaf position in which the diaphragm aperture has reached an irreducible minimum.

oBJEcTs OF THE INVENTION The general object of my present invention is to provide an improved diaphragm of this type having means for completely closing the iris aperture, e.g.'for the purpose of allowing the testing of the camera shutter without exposing the film or for protecting the photocathode of a television camera from glare. v

A more specific object of this invention is to provide means in such iris diaphragm enabling complete closure to be achieved with relatively little effort. 1

SUMMARY OF THE INVENTION In accordance with the instant invention, I realize these objects by the provision of an extra leaf which is pivoted to the same ring as the iris leaves, usually the mounting ring, and which is entrainable by one of the control elements through from an outwardly residual aperture upon relative rotation their aforedescribed terminal position, ing to restrict that aperture.

Advantageously, the coupling formations are a slot on the extra leaf and a pin on the coacting control element, the slot preferably having two angularly adjoining sections whose vertex is occupied by the pin in the terminal ring position to accelerate the inward swing of the extra lead upon further rotation. Thus, the slot may be substantially L-shaped and so positioned that the pin, when engaging the shorter leg of the L during the closure movement, exerts a camming effect whereby only a small additional fraction of a turn will suflice to obstruct the diaphragm aperture.

DESCRIPTION OF THE DRAWING of the rings beyond i.e. in a direction tendshowing the aslarly from FIG. 4, that 2 SPECIFIC DESCRIPTION The iris diaphragm shown in the drawing comprises a fixed mounting ring 5 and a rotatable setting ring 7 (shown only in part) centered on a common axis 0. A set of iris leaves 1 and been shown in FIG. 3. Also visible in FIG. 1 are the pivots 4b 4c of two additional iris leaves the entire assembly comprises control leaves. Each iris leaf is the associated control leaf.

In accordance with my present improvement, the assembly further includes an extra leaf 8 (see also FIG. 4) pivoted at 9 to the fixed ring 5 and provided with an L-shaped camming slot 10 engaged by a pin 11 which carried on the control leaf 2 illustrated in FIGS. 1 3. Slot 10 has a longer section or leg A-B and a shorter section or leg B-C; it will be noted, particuthe leg A-B includes an acute angle with a line 2 passing through pivot 9 and vertex B whereas the leg B-C includes an obtuse angle with that line. The location of vertex B is so chosen that pin 11, sliding in leg A-B during the inward swing of the iris leaves from their wide-open position of FIG. 1, reaches that vertex in the terminal position of FIG. 2 in which these leaves define the minimum diaphragm aperture realizable without the aid of leaf 8. In this terminal position pivots 4 and 9 will be seen to lie substantially on a common diameter with the point of articulation 3 between the iris leaf 1 and the control leaf 2 carrying the pin 11. The contours of the iris leaves and of the extra leaf 8 are so chosen that, up to that point, leaf 8 never obstructs the aperture defined by the edge portions of leaves 1 remote from their pivots 6.

It will be apparent that any further rotation of setting ring 7 beyond the tenninal position of FIG. 2, in the clockwise direction tending to reduce the diaphragm aperture, will not cause any appreciable swing of iris leaf 1, in view the diametrically opposite positions of pivot 4 and hinge point 3. Such further rotation, however, brings the pin 11 into contact with the shorter leg B-C of slot 10 with a resultant camming action which moves the tip of leaf 8 into a stop position illustrated in FIG. 3 wherein the diaphragm aperture is completely obstructed. I

The angle a, defined by pivots 6 and 9 with the optical axis 0, determines the rotary position in which the pin 11 reaches the vertex B so that the stroke of leaf 8 may be modified by whence it will be apparent that five iris leaves along with five articulated at a hinge point 3 to varying thisangle. Thus, a displaceable mounting of pivot 9- and pin 11 enables adjustment of that angle.

I claim:

1. An iris diaphragm comprising a first ring and a second ring centered on a common axis for relative rotation; a set of iris leaves pivoted at peripherally spaced locations to said first ring; a set of control leaves pivoted at peripherally spaced locations to said second ring, each control leaf being articulated to a respective iris leaf for swinging same, upon relative rotation of said rings in a predetermined direction, toward said axis into a limiting position in which edge portions of said iris leaves remote from their pivots define a restricted aperture; and an extra leaf pivoted to said first ring, one of said control leaves being provided with a pin and said extra leaf being proobstructing said restricted aperture upon relative rotation of said rings in said direction beyond a terminal position corresponding to said limiting position of said iris leaves.

2. A diaphragm as defined in claim 1 wherein said control leaves are arcuate.

r 3. A diaphragm as defined in claim 1 wherein said slot has two angularly adjoining sections with a vertex occupied by said pin in said terminal position of the rings.

4. A diaphragm as defined in claim 3 wherein one of said section includes an acute angle and the other of said sections includes an obtuse angle with a line extending from said vertex to the pivot of said extra leaf.

'5. A diaphragm as defined in claim 4 wherein said slot is substantially L-shaped, said one of said sections constituting the longer arm of the L and being occupied by said pin during the inward swing of said stop leaves. 

1. An iris diaphragm comprising a first ring and a second ring centered on a common axis for relative rotation; a set of iris leaves pivoted at peripherally spaced locations to said first ring; a set of control leaves pivoted at peripherally spaced locations to said second ring, each control leaf being articulated to a respective iris leaf for swinging same, upon relative rotation of said rings in a predetermined direction, toward said axis into a limiting position in which edge portions of said iris leaves remote from their pivots define a restricted aperture; and an extra leaf pivoted to said first ring, one of said control leaves being provided with a pin and said extra leaf being provided with a camming slot receiving said pin and shaped to retain said extra leaf in an outwardly withdrawn position unobstructive of said aperture during normal movement of said iris leaves and to swing said extra leaf into a stop position obstructing said restricted aperture upon relative rotation of said rings in said direction beyond a terminal position corresponding to said limiting position of said iris leaves.
 2. A diaphragm as defined in claim 1 wherein said control leaves are arcuate.
 3. A diaphragm as defined in claim 1 wherein said slot has two angularly adjoining sections with a vertex occupied by said pin in said terminal position of the rings.
 4. A diaphragm as defined in claim 3 wherein one of said section includes an acute angle and the other of said sections includes an obtuse angle with a line extending from said vertex to the pivot of said extra leaf.
 5. A diaphragm as defined in claim 4 wherein said slot is substantially L-shaped, said one of said sections constituting the longer arm of the L and being occupied by said pin during the inward swing of said stop leaves.
 6. A diaphragm as defined in claim 4 wherein said slot and said extra leaf are contoured to prevent said extra leaf from obstructing the aperture defined by said edge portions during occupancy of said one of said sections by said pin.
 7. A diaphragm as defined in claim 3 wherein the pivot of said extra leaf, the pivot of said one of said control leaves and the point of articulation of the latter leaf with the corresponding iris leaf lie substantially on a common diameter in said terminal position. 